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61.
T. Jonsson N. Folkeson M. Halvarsson J.-E. Svensson L.-G. Johansson 《Oxidation of Metals》2014,81(5-6):575-596
This paper investigates the influence of 500 ppm HCl in a 5 %O2–95 %N2 atmosphere on the oxidation of the austenitic stainless steel AISI 310S at 500 °C. Laboratory exposures were made for one, 24, 72 and 168 h and the samples were analysed with XRD, SEM/EDX, FIB and TEM/EDX. When exposed in oxygen a thin and protective chromium-rich oxide scale forms. Addition of HCl causes significantly accelerated corrosion. Within the first hour of exposure, accumulations of FeCl2, CrCl2 and NiCl2 forms below the chromium-rich oxide, especially at steel grain boundaries. The chlorine-induced corrosion is suggested to occur through an electrochemical reaction, in which the dissociation of HCl to form chloride ions at the scale surface is coupled to the oxidation of the metal surface beneath the scale by an outwards electronic current and inwards diffusion of chloride ions along oxide grain boundaries. 相似文献
62.
Walter Anduaga Ingemar Svensson Patrick Adlercreutz Bo Mattiasson 《Journal of the American Oil Chemists' Society》1999,76(10):1157-1162
An alkaline acylester hydrolase was partially purified from germinated seeds of Lupinus mutabilis. Hydrolytic activity was absent in the crude extract of ungerminated lupine seed, but it increased and peaked at the fourth
day in the germinating seedling. The purification scheme involved homogenization, centrifugation, acetone precipitation, anion
exchange chromatography, pH precipitation, and hydrophobic interaction chromatography. The acylester hydrolase was purified
126-fold, and the overall activity yield was 10%. The molecular weight estimated by sodium dodecylsulfate-polyacrylamide gel
electrophoresis was 60 kDa. The enzyme had an isoelectric point of 6.2 and showed maximal activity at pH 8.0. The enzyme showed
good stability between pH 5.0 and 9.0. In the pH range 7.0–7.5, enzyme precipitation was observed. The enzyme was stable from
0 to 25°C for 5 h and at 45°C lost 50% of its activity in the same period of time. At higher temperatures, the enzyme showed
low thermal stability. However, the highest initial activity was found to be at 45°C. Nonionic surfactants and cholic acid
enhanced the activity of the enzyme. The activity was reduced by the addition of toluene and isooctane and increased by the
addition of diethyl ether, acetonitrile, methanol, and pyridine. The activity was reduced by 37% in the presence of 1 mM Cu2+ ions. The enzyme-hydrolyzed triolein showing no positional specificity. 相似文献
63.
Rohollah Ghasemi Jakob Olofsson Anders E. W. Jarfors Ingvar L. Svensson 《International Journal of Cast Metals Research》2017,30(3):125-132
This study focuses on the modelling and simulation of local mechanical properties of compacted graphite iron cast at different section thicknesses and three different levels of silicon, ranging from about 3.6% up to 4.6%. The relationship between tensile properties and microstructure is investigated using microstructural analysis and statistical evaluation. Models are generated using response surface methodology, which reveal that silicon level and nodularity mainly affect tensile strength and 0.2% offset yield strength, while Young′s modulus is primarily affected by nodularity. Increase in Si content improves both the yield and tensile strength, while reduces elongation to failure. Furthermore, mechanical properties enhance substantially in thinner section due to the high nodularity. The obtained models have been implemented into a casting process simulation, which enables prediction of local mechanical properties of castings with complex geometries. Very good agreement is observed between the measured and predicted microstructures and mechanical properties, particularly for thinner sections. 相似文献
64.
This study is focused on the identification of structural features that determine the selectivity of dopamine receptor agonists toward D1 and D2 receptors. Selective pharmacophore models were developed for both receptors. The models were built by using projected pharmacophoric features that represent the main agonist interaction sites in the receptor (the Ser residues in TM5 and the Asp in TM3), a directional aromatic feature in the ligand, a feature with large positional tolerance representing the positively charged nitrogen in the ligand, and sets of excluded volumes reflecting the shapes of the receptors. The sets of D1 and D2 ligands used for modeling were carefully selected from published sources and consist of structurally diverse, conformationally rigid full agonists as active ligands together with structurally related inactives. The robustness of the models in discriminating actives from inactives was tested against four ensembles of conformations generated by using different established methods and different force fields. The reasons for the selectivity can be attributed to both geometrical differences in the arrangement of the features, e.g., different tilt angels of the π system, as well as shape differences covered by the different sets of excluded volumes. This work provides useful information for the design of new D1 and D2 agonists and also for comparative homology modeling of D1 and D2 receptors. The approach is general and could therefore be applied to other ligand–protein interactions for which no experimental protein structure is available. 相似文献
65.
Ingela Fritzson Bo Svensson Dr. Salam Al‐Karadaghi Prof. Björn Walse Dr. Ulf Wellmar Dr. Ulf J. Nilsson Prof. Dorthe da Graça Thrige Dr. Stig Jönsson Dr. 《ChemMedChem》2010,5(4):608-617
A strategy that combines virtual screening and structure‐guided selection of fragments was used to identify three unexplored classes of human DHODH inhibitor compounds: 4‐hydroxycoumarins, fenamic acids, and N‐(alkylcarbonyl)anthranilic acids. Structure‐guided selection of fragments targeting the inner subsite of the DHODH ubiquinone binding site made these findings possible with screening of fewer than 300 fragments in a DHODH assay. Fragments from the three inhibitor classes identified were subsequently chemically expanded to target an additional subsite of hydrophobic character. All three classes were found to exhibit distinct structure–activity relationships upon expansion. The novel N‐(alkylcarbonyl)anthranilic acid class shows the most promising potency against human DHODH, with IC50 values in the low nanomolar range. The structure of human DHODH in complex with an inhibitor of this class is presented. 相似文献
66.
Tröger Armin Svensson Glenn P. Galbrecht Hans-Martin Twele Robert Patt Joseph M. Bartram Stefan Zarbin Paulo H. G. Segraves Kari A. Althoff David M. von Reuss Stephan Raguso Robert A. Francke Wittko 《Journal of chemical ecology》2021,47(12):1025-1041
Journal of Chemical Ecology - The obligate pollination mutualism between Yucca and yucca moths is a classical example of coevolution. Oviposition and active pollination by female yucca moths occur... 相似文献
67.
Key technologies for IMT-advanced mobile communication systems 总被引:2,自引:0,他引:2
Wijting C. Doppler K. Kalliojarvi K. Svensson T. Sternad M. Auer G. Johansson N. Nystrom J. Olsson M. Osseiran A. Dottling M. Luo J. Lestable T. Pfletschinger S. 《Wireless Communications, IEEE》2009,16(3):76-85
WINNER is an ambitious research project aiming at identification, development, and assessment of key technologies for IMTAdvanced mobile communication systems. WINNER has devised an OFDMA-based system concept with excellent system-level performance for flexible deployments in a wide variety of operating conditions. The WINNER system provides a significant step forward from current 3G systems. Key innovations integrated into the system concept include flexible spectrum usage and relaying, adaptive advanced antenna schemes and pilot design, close to optimal link adaptation, hierarchical control signaling, and a highly flexible multiple access scheme. The end-to-end performance assessment results demonstrate that the WINNER concept meets the IMTAdvanced requirements. 相似文献
68.
JS Laméris J Stoker HG Nijs M van Blankenstein OT Terpstra 《Canadian Metallurgical Quarterly》1992,136(30):1462-1466
Self expandable stents were placed percutaneously in 105 patients with malignant biliary obstruction. Stent diameter was 1 cm; length, 3.5-10.5 cm. Of the 60 patients with common bile duct obstruction, 50 died 0.2-12 months (median 3 months) after stent insertion. Two patients developed recurrent jaundice and cholangitis after 6 and 12 months, respectively. One patient underwent reintervention. Ten patients, one after a successful reintervention, were alive without jaundice 1-8 months (median 5 months) after stent placement. Of the 45 patients with hilar lesions, 26 died 0.7-18 months (median 5 months) after stent placement, five of them with signs of cholangitis. Nineteen are alive 1-21 months (median 7 months) afterwards. Reinterventions were carried out in 13 patients (29%). The most common cause of stent malfunction was tumour overgrowth. Stent-related complications were seen in three patients. 相似文献
69.
Cleavage motifs of the yeast 20S proteasome beta subunits deduced from digests of enolase 1 总被引:3,自引:0,他引:3
AK Nussbaum TP Dick W Keilholz M Schirle S Stevanovi? K Dietz W Heinemeyer M Groll DH Wolf R Huber HG Rammensee H Schild 《Canadian Metallurgical Quarterly》1998,95(21):12504-12509
The 436-amino acid protein enolase 1 from yeast was degraded in vitro by purified wild-type and mutant yeast 20S proteasome particles. Analysis of the cleavage products at different times revealed a processive degradation mechanism and a length distribution of fragments ranging from 3 to 25 amino acids with an average length of 7 to 8 amino acids. Surprisingly, the average fragment length was very similar between wild-type and mutant 20S proteasomes with reduced numbers of active sites. This implies that the fragment length is not influenced by the distance between the active sites, as previously postulated. A detailed analysis of the cleavages also allowed the identification of certain amino acid characteristics in positions flanking the cleavage site that guide the selection of the P1 residues by the three active beta subunits. Because yeast and mammalian proteasomes are highly homologous, similar cleavage motifs might be used by mammalian proteasomes. Therefore, our data provide a basis for predicting proteasomal degradation products from which peptides are sampled by major histocompatibility complex class I molecules for presentation to cytotoxic T cells. 相似文献
70.